Ball swage for reducing tubes

ABSTRACT

A device for reducing tubes. Two annular sets of balls are axially spaced in a revolving drawing head and successively engage a tube as it is drawn through the head. The number of balls in one ring is different from that in the other, thereby smoothing out any helical grooves and ridges formed by the first set. The balls are individually mounted in sockets in threaded slugs carrying micrometer markings.

United States Patent 9] Quinlan 1 Apr. 17, 1973 BALL SWAGE FOR REDUCINGTUBES 2,352,040 6/1944 Ungerer ..72/236 [76] Inventor: Frank B. Quinlan,i947 Hetrik FOREIGN PATENTS OR APPLICATIONS Avenue, Richland, Wash.99352 1,368,114 6/1964 France ..72/75 [22] Filed: Apr. 23, 1971 [21]Appl. No; 136,791 Primary Examiner-Powell A. Larson Attorney-RobertKeith Sharp [52] US. Cl. ..72/35, 72/75, 72/77 [57] ABSTRACT [51] Int.Cl. ..B21c 3/08 58 Field of Search ..72/35, 36, 75, 77, A i tubes "fsets balls are axially spaced in a revolving drawing head and 72/78,236, 468; 81/168; 151/57 successively engage a tube as it IS drawnthrough the 56 R f Cted head. The number of balls in one ring isdifferent from 1 e erences I that in the other, thereby smoothing outany helical UNITED STATES PATENTS grooves and ridges formed by the firstset. The balls are individually mounted in sockets in threaded slugsl,203,306 10/1916 Brinkman ..72/75 micrometer markings 629,245 7/1899Frank ..72/75 1,637,590 8/1927 Robinson ..8l/l68 9 China, 6 Drawing 1w H.27 m I Z 2 4a 1 [6 Y s A 4 5 I I I 5 H a 3] 5 a I I/ "Z z v Z 20 -22 2727 \Tlllfllfllllllll/ll/j lllli llllfi 11115 11141111 1 ll 11 1a lPAIENTED sum 1 UF 2 INVENTOR. Frank 5. Quinlan BYW 1W Afforzzay BALLSWAGE FOR REDUCING TUBES BACKGROUND AND OBJECTS OF THE INVENTION Tubeshave conventionally been drawn or reduced in size and/or thickness bybeing pulled through a stationary die. The outer diameter is determinedby the diameter of the die, the inner diameter by that of a mandrelsupported within the die on a rod which passes through the tube.

The above arrangement produces tremendous friction, with very severelubrication problems.

A modification of the above involves the replacement of the stationarydie by a rotating ring of balls, much like a ball bearing. Such a deviceis shown in U.S. Pat. No. 1,440,527, granted Jan. 2, l923, to L. H.Brinkman. This type of apparatus has come to known as a ball swage. Theball swage greatly reduces the lubrication problems, permitting the useof ordinary machine oil, rather than the exotic lubricants required inthe stationary-die machine s. However, it introduces problems of itsown. Each ball produces a helical groove on the exterior of the tube.Supposedly, successive balls will obliterate the tracks of precedingones, but as drawing speed is increased in relation to the number ofrevolutions per minute of the drawing head, that is not always the caseand the surface of the tube has a slight ripple which may exceedallowable tolerances, particularly in high precision work. This is mostlikely to occur in the case of relatively large tubes, for example thosethree inches or more in diameter. The effect is less pronounced when theball swage includes two rings of balls rotating in opposite directionsas shown in U. S. Pat. No. 1,414,500, granted to L. H. Brinkman on May20, 1922. This arrangement, however, complicates the drive.

Another problem in connection with the ball swage is the rapid wear onthe balls, which make point contact with the drive mechanism. TheBrinkman US. Pat. No. 1,440,527 referred to above seeks to minimize thisby elaborate means for producing a complicated rotational movement ofthe individual balls to equalize the wear.

Another defect of known ball swages is the limited range of tube sizeswhich can be handled by any one rtor.

Accordingly, one object of my invention is to provide a ball swage whichwill eliminate or reduce the ripple effect produced by prior deviceswithout necessarily employing oppositely rotating ball dies.

Another object is to provide a ball swage in which the balls makesurface contact with the driving means to reduce the wear on the balls.

Another object is to provide a means for accurately controlling theouter diameter of the tube.

Another object is to provide a ball swage having a wide range ofadjustability, enabling it to handle tubes of many different sizes.

THE DRAWINGS In the drawings,

FIG. 1 shows diagrammatically the general arrangement of the ball swage.

FIG. 2 shows a partial longitudinal sectionof the r0- tary drawing headand associated parts.

FIG. 6 is a longitudinal sectional view of a modified form ofone oftheplugs 21, 21'. I

SUMMARY OF THE INVENTION My invention involves the use in a ball swageof two rotating annular sets, or rings, of balls rotated in the samedirection at the same speed. Preferably, though not necessarily, theyare mounted in a single rotor. The number of balls in the two sets aredifferent so that the relationship of the helical paths produced byindividual balls in one set will be different from the relationship ofthe paths produced by the balls of the other set. Preferably, thenumbers of balls in the two sets should have no common integral divisorexcept one. For example, if there are eight balls in one set there maybe five or seven in the other.

In order to reduce and equalize the wear on the balls and provide fortheir adjustment, I mount the balls in hemispherical sockets formed inindividual threaded plugs. These plugs have micrometer markings on theirouter ends and are capable of adjustment over a considerable range, say1 inch or more.

DETAILED DESCRIPTION Referring to FIG. 1, 1 represents the frame orsupport, normally part of a conventional draw bench, such as is shown,for example, in the right-hand portion of FIG. 1 of Brinkmans U. S. Pat.No. 1,414,500. Rotary die or drawing head 3 is mounted for rotation inball or roller bearings 5. It is shown as provided with a V-belt pulley7, but may be driven by any suitable means, such as a gear train. Therotary die 3 includes two annular sets of balls 9, 9', which engage thetube 11 which is to be reduced. Within the tube is a plug or mandrel 13,carried by rod 15, which in turn is swiveled by ball-joint 16 on anysuitable support 17. The tube is drawn through the die by gripper 19which is attached to the pulling mechanism of the draw bench (notshown).

Reference is now made to FIGS. 2, 3, and 4 where the details of rotarydie 3 and its mounting are shown. The frame 1 carries a fixed sleeve 2.Rotor 3 is journaled in a removable sleeve 4 by roller or ball bearings5. In use, sleeves 2 and 4 are locked together by a stud 10 or otherlocking means which can be disengaged to permit movement of sleeve 4.Sleeves 2 and 4 are provided with apertures 6 and 8, respectively. Innormal use, they are non-aligned, as shown in FIGS. 3 and 4. Afterdisengagement of stud 10, sleeve 4 can be rotated to cause them to matchup, providing access to rotor 3 for a purpose to be explained later.Rotary die 3 includes a rotor body 20 having an accurately machinedinner surface 22, a portion of which is frusto-conical. Threaded plugs21, 21' are mounted in two annular sets. (The parts of one set areindicated throughout by the primed reference characters.) The plugs areshown as made of steel with bearing blocks 23, 23 of aluminum bronze,which are sweated or threaded in the plug body. Alternatively, theentire plug may be made of aluminum bronze. The balls 9, 9' are held inhemispherical cavities, in which they rotate freely, in bearing blocks23, 23' by retainers 25, 25 which are threaded on plugs 21, 21. Feltpads 27, 27, held by tabs 29, 29 on retainers 25, 25', serve tolubricate and clean balls 9, 9. Grooves 31, 31', which will be discussedin more detail later, carry lubricant, by centrifugal force, along theplugs for cooling purposes. The

' lubricant is squirted into the interior of the rotor from theleft-hand end in considerable quantities, conveyed by the frustoconicalsurface 22, and serves to lubricate and cool the tube 11, the balls9, 9'and the rotor body Referring to FIGS. 3 and 4, it will be noted thatthere are eight plugs 21 and associated balls 9 and five plugs 21 andassociated balls 9'. Hence, balls 9' will not follow the tracks of balls9 and will tend to smooth out grooves and ripples. It may be founddesirable, however, to slightly adjust the drawing speed since it ispossible under specific ratios of drawing speed and rate of rotation ofthe rotary die, for one ball 9' to follow the track of one ball 9.

While I have shown the balls 9, 9 as having the same diameter, they maybe of considerably different size, the balls 9' being preferably thelarger. Under some conditions, this aids in the smoothing action.

The adjustment of plugs 21, 21' will now be described. The sleeve 4 isunlocked from sleeve 2 and rotated to align apertures 6 and 8, givingaccess to the outer ends of the plugs. The plugs are threaded at 33,

33' with the pitch being such as to provide a convenient micrometerrelationship. If English units are to be used, forty threads per inch isa convenient value. Referring to FIG. 5, it will be notedv that the plug21 has its circumference marked by 25 evenly spaced indices 34, whilerotor body carries a single index mark, 35. Thus each division on theplug indicates a movement of 0.00l inch when the plug is turned.

, In the periphery of each plug there are five grooves 31 and in therotor body there are five grooves 37. Matching of a groove 3l with agroove 37 permits insertion of a locking pin. The grooves 37 are evenlyspaced about the axis of the plug, but the spacing of grooves 31 varies.For example, they may be located at zero, four, six," l 2, and l 8. Theprinciple is similar to that of a Vernier. With. this arrangement,whenever one of the indices on plug 31 is aligned with index 35, agroove 31 will be aligned with a groove 37 and a locking pin (not shown)may be inserted to fix the plug 31 in place. The essentialcharacteristic of the spacing of grooves 31 is that the variations inspacing of the grooves are integral multiples of the spacing of theindices. It is desirable to provide swingable tabs 39 which may beturned to cover the matched grooves 31-37 to prevent the locking pinfrom being thrown out by centrifugal force. Sockets 4] provide forinsertion of a tool to turn the plugs 21'. A removable cover plate 43forming part of frame 1 provides access. Oil thrown out into the spacebetween rotor and cylinder 4 drains away through a hole (not shown).

In FIG. 6 l have shown a modified form of plug 121.

It will be noted that in this modification, the bearing block forms anextension of the plug. By having in stock plugs of the forms shown inFIG. 6, in addition to those shown in FIG. 2, the operator can worktubes in a wide variety of sizes, since the individual plugs areadjustable over a range of an inch or more.

OPERATION The tube is pulled between mandrel 13 and rotary die 3 bygripper 19. The tube is thinned and lengthened because of thecooperative action of balls 21, 21 and mandrel 13. Because of the twosets of balls 21, 21 and because there is a different number of balls ineach set, a particularly smooth finish is produced.

In order to accurately determine the exterior diameter of the tube, theoperator proceeds as follows. A stepped plug guage is provided. Thelarger portion fits in surface 22, thus centering the guage on the axisof rotation of the die. The smaller portion has an accurately knowndiameter approximating the desired external diameter of the finishedtube. Plugs 21, 21 are screwed in until balls 9, 9 touch the surface ofthe plug guage. Using the micrometer markings, the operator thenadvances or retracts the necessary amount to give the desired diametertube.

While I have described a specific embodiment of my invention, it will beapparent that various changes can be made. For example, while the twoannular sets of balls are, in my preferred embodiment, mounted in thesame rotor, they could, if desired, be mounted in separate rotorsrotated in the same direction and at the same speed. i

Moreover, while one rotary die of the type I have shown produces verysmooth metal, it may be desirable for even greater smoothness or forother purposes, e.'g., to eliminate torsional stresses in the tube, toutilize two such dies in tandem rotating in opposite directions.

I therefore wish my invention to be limited only by the scope of theappended claims.

' The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows: I

1. In a tube drawing apparatus comprising a mandrel adapted to support atube from its inside, die means arranged to surround said mandrel andengage said tube and means for drawing said tube between said mandreland said die means, the improvement wherein said die means comprises atleast a first and 'a second annular set of substantially evenly spacedfreely rotatable balls adapted to form a die and engage said tube, andmeans for rotating said sets of balls about the axis of said tube in thesame direction at the same'rotational speed, the number of balls in oneof said sets being different from the number of balls in the other set,whereby the balls of the second set will tend to smooth out any rippleson the outer surface of the tube formed by the first set.

2. A tube drawing apparatus as defined in claim 1 wherein said two setsof balls are mounted in a single 3. In a tube drawing apparatuscomprising a smoothly cylindrical mandrel adapted to support a tube fromits inside, a rotary die means comprising a rotor body annular in crosssection surrounding and coaxial with said mandrel carrying ballsarranged to engage said tube, means for drawing said tube between saidmandrel and said die means, and means for rotating said rotor about itsaxis, the improvement wherein said rotary die means comprises:

a. a first annular set of radial plugs in said rotor body surroundingsaid axis, said plugs being threaded in said rotor body, each plughaving a substantially hemispherical socket in its radially inner end, aball mounted in, and free to rotate in, each socket, and retaining meansfor retaining the balls in the sockets, said balls projecting radiallyinwardly beyond the inner surface of said rotor body, and

b. a second annular set of plugs and associated balls in said rotor bodyof substantially the same form and arrangement as said first set ofplugs and balls, the number of plugs in said second set being differentfrom the number in said first set.

4. A rotary die for drawing tubes comprising a rotor body annular incross section, mounted for rotation about its axis, an annular set ofradial plugs in said rotor body surrounding said axis, said plugs beingthreaded in said rotor body, each plug having a substantiallyhemispherical socket in its radially inner end, a ball mounted in, andfree to rotate in, each socket, and retaining means for retaining theballs in the sockets, said balls projecting radially inwardly beyond theinner surface of said rotor body, indicia on the outer end ofeach ofsaid plugs, an index marking on said rotor body adjacent each of saidplugs and corresponding sets of grooves in said plug and said rotorbody, the grooves extending longitudinally of said plugs, the grooves inone member being evenly spaced and the grooves in the other memberhaving a different spacing, the variations being multiples of thespacing of the indices, whereby, when any one of said indicia is alignedwith said index marking, a groove in said plug will be aligned with agroove in said rotor body and said plug may be locked in position byinsertion of a pin.

5. A device as defined in claim 4, wherein said grooves extend theentire length of said plugs, thereby serving as cooling means.

6. A device as defined in claim 3 and further comprising pads attachedto said retaining means and serving to clean and lubricate said balls.

7. A device as defined in claim 1 wherein the numbers of balls in thetwo sets have no integral common divisor other than unity.

8. A device as defined in claim 3 wherein the number of balls in the twosets have no integral common divisor other than unity.

9. A device as defined in Claim 1 wherein the individual balls of thesecond set are larger in diameter than the individual balls of the firstset.

1. In a tube drawing apparatus comprising a mandrel adapted to support atube from its inside, die means arranged to surround said mandrel andengage said tube and means for drawing said tube between said mandreland said die means, the improvement wherein said die means comprises atleast a first and a second annular set of substantially evenly spacedfreely rotatable balls adapted to form a die and engage said tube, andmeans for rotating said sets of balls about the axis of said tube in thesame direction at the same rotational speed, the number of balls in oneof said sets being different from the number of balls in the other set,whereby the balls of the second set will tend to smooth out any rippleson the outer surface of the tube formed by the first set.
 2. A tubedrawing apparatus as defined in claim 1 wherein said two sets of ballsare mounted in a single rotor.
 3. In a tube drawing apparatus comprisinga smoothly cylindrical mandrel adapted to support a tube from itsinside, a rotary die means comprising a rotor body annular in crosssection surrounding and coaxial with said mandrel carrying ballsarranged to engage said tube, means for drawing said tube between saidmandrel and said die means, and means for rotating said rotor about itsaxis, the improvement wherein said rotary die means comprises: a. afirst annular set of radial plugs in said rotor body surrounding saidaxis, said plugs being threaded in said rotor body, each plug having asubstantially hemispherical socket in its radially inner end, a ballmounted in, and free to rotate in, each socket, and retaining means forretaining the balls in the sockets, said balls projecting radiallyinwardly beyond the inner surface of said rotor body, and b. a secondannular set of plugs and associated balls in said rotor body ofsubstantially the same form and arrangement as said first set of plugsand balls, the number of plugs in said second set being different fromthe number in said first set.
 4. A rotary die for drawing tubescomprising a rotor body annular in cross section, mounted for rotationabout its axis, an annular set of radial plugs in said rotor bodysurrounding said axis, said plugs being threaded in said rotor body,each plug having a substantially hemispherical socket in its radiallyinner end, a ball mounted in, and free to rotate in, each socket, andretaining means for retaining the balls in the sockets, said ballsprojecting radially inwardly beyond the inner surface of said rotorbody, indicia on the outer end of each of said plugs, an index markingon said rotor body adjacent each of said plugs and corresponding sets ofgrooves in said plug and said rotor body, the grooves extendinglongitudinally of said plugs, the grooves in one member being evenlyspaced and the grooves in the other member having a different spacing,the variations being multiples of the spacing of the indices, whereby,when any one of said indicia is aligned with said index marking, agroove in said plug will be aligned with a groove in said rotor body andsaid plug may be lOcked in position by insertion of a pin.
 5. A deviceas defined in claim 4, wherein said grooves extend the entire length ofsaid plugs, thereby serving as cooling means.
 6. A device as defined inclaim 3 and further comprising pads attached to said retaining means andserving to clean and lubricate said balls.
 7. A device as defined inclaim 1 wherein the numbers of balls in the two sets have no integralcommon divisor other than unity.
 8. A device as defined in claim 3wherein the number of balls in the two sets have no integral commondivisor other than unity.
 9. A device as defined in Claim 1 wherein theindividual balls of the second set are larger in diameter than theindividual balls of the first set.